haha, yes I get your point. Perhaps once the node submission preview button is clicked the node gets parsed through a basic handler, something like:

my $paragraph_marker = '<p>';
my $break_marker = '<br>';

if ( $line_count > $x ){
    return "that's a lot of text, maybe you should include some <readm
+ore> tags";
}

if ( $paragraph_count == 0 && 
     $break_count == 0 && 
     $line_count > $y){
         return "you haven't formatted your post. It will be easier to
+ read if you separate your paragraphs with <p> tags.";
}
[download]

of course though, that'll take a bit of work to achieve, and it still won't stop the problem unless people read the warning message(s), which they don't seem to be doing currently...